Saw a yellow and black bird, oriole-sized, that I haven't seen before.
(Hayward, CA, USA)
The male and its mate flew across our back yard a couple of times. The bird was brilliant yellow with black wings, about the size of a blackbird or oriole. I was unable to see the beak shape, so don't know if it was an insect or seed-eater.
I haven't seen the bird before in our Hayward, CA area in our 21-years' residence. There appeared to be no black on the male's head. The wings and possibly the tail were black. It was brilliant yellow in early July, long after the much smaller goldfinches have shed their mating plumage. The female could have been a dull yellow, buff, or brown. I didn't see her clearly. I believe she may have had a pale yellow or buff head, and a brown body.
By your description it sounds like Yellow-headed Blackbirds. Are there marshes nearby? That's where they like to live. They have a harsh strange call that has nothing pretty about it.